Y'all need to clearly state your design decisions and expectations for guild participation and team usage.
Currently, It just makes no sense. From what I have seen, the best teams can get 6-7% on a good run. So you are looking at 400%/6%=66.67 perfect teams in the guild. That still a total of 333 gear 10-11 people in a guild or 6 maxed out perfect toons per person in 50 person guild.
That's a great run and appears to be near the dmg cap that is theoretically possible currently due to the enrage mechanics.
You cannot go from having guilds only needing 5 perfect characters to 333 perfect toons to complete heroic, or realistically from 125-150 sub-optimal to 1000+ sub-optimal toons and not expect backlash.
A jump to around 500 would be hard for most guilds to stomach and 500 would be if each tiers life was cut in half. TI says goal is 2% which is 50x4x5 for a total of 1000 min toons needed in guild. That's insane. I play everyday and get monthly subscription. I'm not even close to that level to pull my weight much less cover for lower powered guild members.
There was nothing wrong with TMR being able to solo a phase. Your problem in Rancor was that TMR was the solution for all 4 phases. Each phase should have a solution. It gives guilds something to work for. For example, mine just started doing T7 cuz we just got enough members with right TMR guys. Pick a solution per phase AOE, TMR, cleanse, anti-specific toons like jawas.
You also can't balance anything around whales (they pay to have all solutions to finish content immediately) and 50 members with all members having the right mix. It needs to be designed that others can carry the load otherwise mixed level guilds make no sense. Doing so penalizes normal guilds who are mix of participation activity and mix levels.
For the love of good, communicate. Communicating simple things allows you to avoid this backlash. The community think this raid is broke based on previous experiences because you provided no alternative baseline of expectations.
